Does using a monitor with a laptop decrease FPS

I recently bought a Surface Book 2 13.5 for uni and the occasional gaming. I really only play Overwatch and I have been suffering major FPS issues. I connect my laptop to a external monitor AOC U2879VF via a USB-C to HDMI adapter. It has a 1050 GTX and i7-8650U CPU. I have a fan blowing onto the back of the laptop (on the Windows logo) and charger plugged in with the slider at Best Performance when I play.

When I play on the laptop monitor, on 1920x1080 75% render and all settings on low/off with 300 FPS cap, I easily get above 100 FPS. GPU usage hits 99% and CPU hits around ~65% with both hovering around mid 50°C.

However, when I connect to my external monitor my FPS decreases dramatically with the same settings. The GPU hits 99% but then decreases to <50°C and CPU decreases to around 20% and <50°C. My FPS drops to <50.

I do not understand why there is a major decrease in performance when I am connected to the external monitor compared to the laptop monitor. I use MSI Afterburner to monitor these % and °C. The integrated graphics arent being used when connected to the external monitor since the % usage stays the same. Ive searched for this problem with other users and I havent found anyone with the same issue as me.

I have tried many potential fixes like disabling HEPT, setting OW to use NVIDIA GPU in NVIDIA control panel, ticking Disable full-screen optimisations in OW properties and deleting the OW Settings_v0 in OW folder. I use Driver Easy to check for updates and my NVIDIA GPU driver is up to date. I am truly stuck, please help.

kdy:

connect my laptop to a external monitor AOC U2879VF via a USB-C to HDMI adapter.

Any way you can try a full HDMI->HDMI cord? It could be an error with the conversion of data from GPU to USB to HDMI again

If that doesnt work or isnt possible, lets check to see what your PC is actually doing during the performance issues. Grab hwmonitor and play a game until it crashes. Once it does, check the max column of your test for CPU/GPU overheating. If those are getting too hot, clean the PC and take it to a PC tech if that doesnt fix the overheating - thatd probably mean some of the heat hardware needs maintenance or replacement.

If you dont see anything, lets snag some screenshots:

1. Maximize the HWMonitor window and expand all the nodes on the left
2. Scroll all the way up
3. Take a screenshot with the Print Screen (prtscn) key
4. Open up the program Paint and press ctrl+v to paste in the test
5. Crop the screen if you want to only show the test, then save it as Test1.JPG
6. Scroll all the way down, then repeat steps 3-5.
7. Upload them somewhere like imgur and link us to the results. Well use those to look for more options.

If you get link errors, just link it between two ` marks, itll break the link and let you post it.

looks like this